Automatic stacking



April 30, 1968 M. L. STRYDOM AUTOMATIC STACKI NG Filed June 8, 1966 25 llmwmc United States Patent 3,380,781 AUTOMATIC STACKING Mauritz L. Strydom, Stellenbosch, Cape Province, Republic of South Africa, assignor to Tobacco Research & Development Institute (Proprietary) Limited Filed June 8, 1966, Ser. No. 556,029 Claims priority, application Republic of South Africa, June 17, 1965, 65/3,193, 65/3,195 4 Claims. (Cl. 302-31) ABSTRACT OF THE DISCLOSURE An automatic stacking device has a conduit for conveying articles, and jets of air are injected through the base of the conduit to cause the articles to fioat on a cushion of air. The jets are arranged in two rows parallel to the walls of the conduit and the jets in each row are inclined towards the other row.

This invention relates to automatic stacking which can be applied between two points where successive operations are being carried out on articles which may be en route to the second point at a faster rate than the rate at which they can :be handled at that point. Thus the invention provides means which in effect stores surplus articles and 'is adapted to release them upon demand.

Thus if, say, a filling machine filling boxes supplies a wrapping machine and the machines start and stop independently, eg for adjustment, some means must be provided to stack the boxes in a constant and correct orientation and sequence between the filling machine and the wrapping machine. As far as the applicant is aware very few devices to fulfil this storing function are available and all these devices involve complicated mechanical arrangements with stepping mechanisms and the like. It is true that these mechanical devices store articles in the correct orientation, but after a period of storage, it is the last article into the store which is released and not the first one in. Thus it may happen that an article received into the store gets held up for a long time, unless the store is completely emptied at the end of each working shift.

An object of the invention is to provide an automatic stacking device which stacks articles and unstacks them in the same sequence as they were originally stacked.

An automatic stacking device according to the invention consists in a convoluted conduit adapted to convey articles to be stacked from a high level to a low level; means to feed articles into the conduit at the high level; means to stop and release articles at the low level; and means for causing gas so to flow in the conduit as to space articles from the walls of the conduit and to keep the articles floating in the conduit even when they are stationary.

The conduit may be a trough through the base of which air-is caused to flow or the conduit may be a pipe in which gas flows from the high level to the low level.

The trough in effect is a conveying system of the kind described, for example, in US. patent specifications Nos. 2,805,898 and 3,180,688 adapted for automatic stacking purposes. The pipe is in effect a pneumatic conveyance system adapted for stacking purposes.

The conduit may be convoluted in any suitable way that may be dictated by the space available for a stacking device. In practice it has been found convenient to have a conduit convoluted to form a vertical spiral. The space inside the spiral may then be occupied by additional electrical and pneumatic equipment required to operate the stacker.

The invention is further discussed with reference to the accompanying drawings, in which 3,380,781 Patented Apr. 30, 1968 "ice FIGURE 1 is a part view of a stacking device of one embodiment of the invention,

FIGURE 2 is an enlarged sectional view of part of the device,

FIGURE 3 is a sectional view of a modification, and

FIGURE 4 is a view of a stacking device of another embodiment of the invention.

The stacking device shown in FIGURES 1 and 2 consists in an elongated trough 5 convoluted into a vertical spiral around a drum 6.

The trough 5 is composed of side walls 7 and a base 8 which surmount-s a windbox 9. The windbox 9 communicates atspaced points with the interior of the drum 6 which is charged with air under pressure. The base 9 is pierced with two rows of jets 10 inclined towards one another to cause amplification of the cushion pressure. In practice an angle of inclination of 28 has been found to give the best results. In the drawings another series of jets 11 are shown. The jets 11 are inclined in the direction of slope of the trough 5 at an angle of about 25.

The jets 10 are a'bout 1.3 mm. in diameter, spaced about 5 mm. apart and are always present. The jets 11 are spaced about 2.5 cm. apart and are optional.

The pitch of the spiral to which the trough 5 is formed is so chosen that the downward inclination of the base 8 is at least minutes. If the chosen pitch gives too gradual a slope for fast enough gravitational movement of articles around the spiral, the jets 10 may be provided.

In horizontal planes the bases 8 are banked to counteract centrifugal force. This is shown in FIGURE 1 where the line 12 indicates the plane containing the base 8 and the line 13, a horizontal plane. The angle 5 must not exceed 4. Thus a line drawn across the width of the base 8 is in substance horizontal.

In use articles to be stacked are introduced at the top of the trough 5 by any suitable means such as a conveyor belt. Articles gravitate down the spiral on a cushion of air and 'at the foot they are released by any suitable gate (not shown). If the demand equals, or is greater than, the supply, the articles pass through the device at speed. If the demand is lower than the supply, or ceases, the gate stops some or all of them and there is a build-up of articles along the spiral, i.e. they become stacked in the spiral. As the demand continues or is resumed, the articles first into the stack are first released by the gate.

As described above the drum 6 is pressurized. However, the windbox 9 may be fed by a suitable manifold in which case the pressure generating equipment may be housed inside the drum.

FIGURE 3 illustrates means for increasing the stacking capacity. In this case a single conduit provides two troughs side by side on the same windbox 9.

The stacker shown in FIGURE 4 is formed from a pipe I 20 which is convoluted into a vertical spiral as shown.

The pipe has a suitable cross-section for conveying the articles in question by normal pneumatic techniques.

A fan 21 supplies the motive suction. Articles arriving on a conveyor 22 are sucked into the open end 23 of the pipe 20. The articles proceed along the spiral 25 to an air lock 24 of any suitable construction where articles are reelased as required on to a conveyor 26.

Suction is applied mainly through a valve 28 to a suction 'box 27 at the end of the pipe 20 and articles gravitate I into the air lock 24. However, a suction manifold 29 is connected through control valves 30 to the spiral 25 at points more or less evenly spaced 'along the length of the pipe 20 that is in the spiral 25. The valves 28 and 30 are so regulated as to ensure smooth operation on the stacker under all conditions, i.e. from when the stacker is empty to when it is substantially filled.

3 .4 o I claim: 3. The device claimed in claim 2, in which the angle of 1. An automatic stacking device consisting in a conbank is less than four degrees. voluted vtroughed conduit having a base and substantially 4. The device claimed in claim 1, in which the trough upstanding parallel walls, lines across the width of the is convoluted to form a vertical spiral. 'base being substantially horizontal; the conduit being 5 adapted to convey articles from a high level to a low level; References Cited and means to stop and release articles at .the low level; UNITED STATES PATENTS jets piercing the base; and means to cause air to flow through the jets to cause flat bottomed articles in the 1,515,965 11/1924 Pardce 302-3'1 trough to float on a cushion of air, the jets being pro- 10 2,805,898 9/1957 Willis 30229 vided in two rows parallel to the side wall-s and the jets 3,131,974 5/1964 Futer 30231 in each row being inclined towards the other row at an 3,180,688 4/1965 Futer 302-29 angle causing amplification of cushion pressure. 3, 1,165 1/1966 Wallin et va1. 30229 '2. The device claimed in claim 1 in which in the curved 1,270,366 6/1918 Bend 193-12 parts of the convolutions the base is banked to counter- 15 act centrifugal force, ANDRES H. NIELSEN, Primary Examiner. 

